An apparatus of this type is known from SU 457486. This apparatus comprises a tube extending vertically in a cylindrical chamber. The tube extends in the direction of the longitudinal axis of the chamber, sealed at the upper side by a baffle. The tube comprises an exit aperture at its upper side, located opposite the baffle in a preset spaced apart relationship. Below the baffle, the side wall of the chamber comprises apertures.
In the tube comminuted particles are collected forming a plug at a predetermined filling level inside the tube. The plug is accelerated explosively by way of a pressure pulse unit and is propelled from the tube against a baffle. When the particles hit the baffle, very high shearing forces occur resulting in a comminution of the particles. By the excess pressure generated in the pressure pulse unit finely comminuted particles are transported predominantly to the marginal regions of the chamber and discharged from the chamber via the apertures in the side walls. Coarser particles, on the other hand, drop back into the chamber and are returned to the pipe.
Even very hard particles may indeed be comminuted efficiently with this apparatus, which comprises virtually no moving parts and is thus of simple and cost-effective design. However, it suffers from the disadvantage that the particle sizes and particle size distributions of the comminuted particles can be preset and adjusted only inadequately.
In particular, it is disadvantageous that only an undesirable, incomplete and non-reproducible separation of fine and coarse particles comes about when the plug hits the baffle.
It is the object of the invention to make it possible to comminute preferably hard particles with as little constructional effort as possible, in which context the particle sizes of the comminuted particles may be preset as accurately as possible.